1. Field of the Invention
The present invention relates to a printing apparatus, and particularly relates to a printing apparatus capable of selecting a suitable conveyance path from multiple conveyance paths according to a type of printing medium and/or a selected print quality.
2. Description of the Related Art
A printing apparatus such as an inkjet printing apparatus forms an image on a printing medium by moving the printing medium and a printing head, which is used to apply a printing agent, relative to each other. If printing media are relatively soft like plain paper, many printing media can be stacked on an inclined sheet feeding tray, and are separately fed one by one by a sheet feeding roller. Then, the printing medium is fed while changing its feeding path by gently bending along the sheet feeding roller, and then is printed and discharged. Instead, such printing media are housed in a cassette disposed at a lower portion of the apparatus, and are fed one by one by a sheet feeding roller. The printing medium thus fed is bent and conveyed in the reverse direction by the sheet feeding roller, turn-over rollers or other similar rollers. After that, the printing medium is printed and further conveyed.
In contrast, printing is performed on a printing medium, such as a thick printing medium, a printing medium desired not to bend, and also a printing medium, like a CD-R, practically incapable of bending (in essence, a printing medium having a relatively high stiffness), while the printing medium is conveyed entirely in one plane. To this end, a printing apparatus having a conveyance path in one plane in addition to a conveyance path as described above has been proposed and been put into practical use (For example, see Japanese Patents Laid-open Nos. 2002-192782 and 2007-70105). In this description, such a conveyance path in one plane and printing accompanied by a conveyance operation through the conveyance path are referred to as a flat path and flat path printing, respectively.
Japanese Patent Laid-open No. 2002-192782 discloses a configuration including a pair of conveying rollers for conveying a printing medium by nipping the printing medium therebetween from its both sides when printing is performed. With this configuration, a user himself/herself separates and presses together the pair of conveying rollers to set a printing medium. More specifically, in order to perform the flat path printing on a printing medium such as thick paper, the user sets the printing medium by once separating the pair of conveying rollers from each other; horizontally inserting the printing medium into a manual feeding port provided on the back of an apparatus; and then pressing the pair of conveying rollers against each other with the printing medium nipped therebetween. In short, a printing medium is horizontally fed by a user in the sheet feeding operation, whereby the flat path is put into practice without causing the printing medium to bend in the sheet feeding operation.
On the other hand, Japanese Patent Laid-open No. 2007-70105 discloses another configuration including a pair of conveying rollers for conveying a printing medium by nipping the medium therebetween from its both sides. In this configuration, the pair of conveying rollers are automatically separated from and pressed against each other. Moreover, an apparatus with this configuration employs a structure allowing a printing medium to be horizontally inserted into the apparatus from the front of the apparatus. Thus, this configuration has an advantage that the operation needed to be performed by a user is easy.
The foregoing methods described in Japanese Patents Laid-open Nos. 2002-192782 and 2007-70105, however, have several problems. For example, the configuration in which a user manually separates and presses together the conveying rollers as in Japanese Patent Laid-open No. 2002-192782 requires the user's manual operation, which may result in an operational error. Moreover, since a printing medium is inserted from the back of the apparatus, this configuration has a problem of poor operability in setting the printing medium. On the other hand, the configuration described in Japanese Patent Laid-open No. 2007-70105 has good operability because the apparatus has the conveying rollers automatically separated and pressed together and allows a printing medium to be inserted from the front of the apparatus. In some cases, however, the flat path printing is desired on a thin printing medium such as plain paper and photo paper, that is, a relatively soft printing medium, as well as a printing medium having relatively high stiffness as described above. When using such a relatively soft printing medium, a user has difficulty in setting the printing medium with high accuracy even with the configuration allowing the printing medium to be set from the front of the apparatus.